That’s amazing. I was learning behaviourism in undergrad and tried it out on my, then, old and sole cat for mealtime. Although that cat has since gone on, my others all learned from him and it still works, without any conditioning whatsoever!
When Tyson’s tail was injured, we would call when one of us was at the end of the driveway to make sure he didn’t get so excited he hit his happy tail on something. Now, more than six months later, whenever he hears the phone ring and one of us isn’t home, he goes absolutely nuts. So much for good intentions…